Cortical magnification refers to the fact that the number of neurons in the visual cortex responsible for processing the visual stimulus of a given size varies as a function of the location of the stimulus in the visual field. Stimuli occurring in the center of the visual field that have been detected in the fovea of the retina are processed by a very large number of neurons in the primary visual cortex of the occipital lobe, though these neurons handle only a very small region of the central visual field. Conversely, stimuli detected in the peripheral visual field tend to be processed by a much smaller number of neurons in the primary visual cortex.
Cortical magnification reflects an important concept in the field of cognitive neuroscience; the cortical volume, and ultimately the number of neurons allocated to a particular function, typically varies as a function of the significance of the function. For example, since the sense of touch is particularly...